阅读材料，完成下列各题。

       清华大学历史系博士生冯立，是赫赫有名的清华“书神”。

       冯立一直保持着这样一个习惯，每读完一百本书，就要写一篇总结性的文章，从一个主题入手，或谈谈读书所得，或谈谈阅读技巧，最后还要为这一百本书评选出一个前十名的最佳榜单。《在千山万水间枕典席文》《经典的力量》《碎片化阅读时代的碎与读》……这些都是冯立写在每一个“百本大关”的感悟和总结。从大一结束时制定读书计划开始，转眼已是历史系博士二年级的他完成了第十七个一百本读书计划，仔细算一下，相当于一年读二百多本书，平均三天两本。这样的速度，恐怕绝大多数人都是望尘莫及的，更别提长期的坚持的坚持了。

       在想象中，这样一个读书“大神”不仅是上知天文下知地理的，还有可能有些“呆气”。然而在咖啡馆见面时，他与所有普通的清华同学没有什么太大的区别。蓝色的运动上衣，鼓鼓囊囊的旧书包，梳不平的头发，略微有些胖，笑眯眯的。

       当他谈及读书的缘起，也似乎有些普通。只是觉得大学过了一年有些荒废，想看看能读多少本书，没想到上大四上学期就提前完成了三年读完三百本的目标，一读就再也停不下来了。

       一开始他按照香港中文大学的大学生必读书单看了几本，很快就发现，人不可能按照书单一本一本为了达到某个目的、刷到某个成就而读书，读书时顺其自然的，一本接一本。如果你对某一本书感兴趣，可以找到相关的书来看，还可以找书中提到过的其他书来看，慢慢地就会形成自己看书的体系，找到自己搜罗好书的方式。

——Your father was worried about something this morning. Why?
——He wondered         .

阅读理解

    Not every parent looks forward to the day when their child goes off to school. In fact some parents are not sending their children to school at all. Instead they are choosing to teach their children at home. This is called homeschooling. Parents, caregivers, or private tutors educate children individually at home instead of sending them off to be formally educated in public or private schools. In the U.S. only about three percent of children are homeschooled.

    There are many reasons why some parents choose to homeschool. One reason is that some parents do not feel their children are safe in school because of bullying (恃强凌弱). It is said that bullying is very common in the school. Other parents want their children's education to be based on their religion or moral beliefs. Yet other parents think the education in school is not good enough. Homeschooling is also seen as a choice for families that live in rural areas, and families that move frequently.

    There are many different ways to homeschool, and homeschooling allows parents to design lessons based on their children's needs. Families can purchase textbooks to use or create their own materials. Some parents follow a philosophy called unschooling, which allows a child to determine when and how they want to learn based on their natural ability. Some worry that homeschooling means students won't have opportunities to communicate with others.

    To solve this problem, some families have created activities, where a group of homeschooled students will learn and play together and participate in activities that would normally happen in school like field trips.

    Besides, being homeschooled doesn't mean a student cannot go to college. Most colleges accept homeschooled students. And the homeschooled students can get the same degrees, too.

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。